1. Field of the Invention
The present invention relates generally to non-structural, decorative architectural products, and more particularly to a method and apparatus for inexpensively manufacturing highly-durable simulated stone and wood architectural products for buildings, homes and the like.
2. Description of the Prior Art
Historically, natural stone or wood architectural shapes and forms have been cut or carved from natural material to achieve the desired design; that is, to achieve the desired shape, surface contour and surface texture. However, this proved to be a time consuming, high maintenance, and labor-intensive process. Furthermore, the high costs associated with the manufacturing, shipping, handling and installation of the products rendered such products cost prohibitive for many potential purchasers.
As the demand for such products has increased over the years, the architectural stone manufacturing industry has resorted to a casting method wherein a mixture of portland cement, sand and water are poured into a mold form or cavity and allowed to cure for at least several hours. With regard to wood architectural shapes and forms, generally, a natural piece of wood is selected, kiln dried, finished and installed. Like most natural products, wood requires ongoing maintenance and care. Additionally, the limited availability of select cuts of wood is an ongoing concern in the natural wood industry, restricting production and driving up manufacturing costs.
With regard to the cast stone industry, some improvements have been achieved in recent years. Most notably, methods have been developed for spray deposition of a lighter fiber-reinforced version of the cement-based composition. However, the need remains for a simpler, more efficient and more cost effective method of producing stone and wood architectural shapes and forms. Furthermore, it would be desirable to provide such a method whereby the resultant products have a lighter weight, greater environmental durability and dimensional stability, and less residual stress than comparable articles produced using prior art methods.
The present invention provides a method and apparatus for manufacturing simulated cast stone and simulated natural wood architectural products.
In one aspect of the present invention, a mold assembly for manufacturing an article having a simulated stone or wood appearance is provided. The mold assembly generally comprises a mold box having a solid polymer support cradle disposed within the mold box. The support cradle includes a contoured cavity formed in its upper surface, a silicone rubber mold having a lower surface form-fitted to the contoured cavity of the solid support cradle, and a vented mold lid.
In another aspect of the present invention, a method for manufacturing a mold assembly to produce an article having a simulated stone or wood appearance is provided. Initially, a master form having a shape, surface contour and surface texture replicating the shape, surface contour and surface texture of the final product is mounted on a support base. A master mold cradle is provided having an integral cavity having a shape and surface contour substantially identical to the shape and surface contour of the master form, but having dimensions greater than the corresponding dimensions of the master form. The mold cradle is seated over the master form, creating a gap. The gap is subsequently filled with a resilient mold material, such as a silicone mold rubber, the mold material is cured, and the master form and master form base are separated from the master mold cradle.
In a further aspect of the present invention, a method is provided for manufacturing an article having a simulated stone or wood appearance. Initially, a resilient mold having a mold cavity formed in its upper surface is provided supported within a corresponding polymer mold cradle cavity. The mold cavity is initially coated with one or more layers of a mineral fiber reinforced polyester gel face coat and allowed to gel cure for about 30 minutes. Subsequently, a mineral fiber-reinforced acrylic/vinyl ester back coating is applied to the face coating and allowed to gel cure for about 30 minutes. Within a few minutes thereafter, a predetermined volume of mineral fiber-reinforced high-density closed-cell polyurethane polymer is dispensed into the mold cavity, the mold cavity is covered with a vented mold lid, and placed in a press for about 10 minutes. Subsequently, the mold is removed from the press and the composition is allowed to cure for an additional period of about 10 minutes before being removed from the mold. Preferably, a peanut oil and polymer blend is applied to the mold cavity prior to forming the back coat and face coat to facilitate removal of the final product from the mold.
In yet a further aspect of the present invention, an architectural article having a simulated stone or wood appearance is provided. The article is comprised of a mineral fiber-reinforced high-density closed cell polyurethane polymer core, a mineral fiber-reinforced polyester gel face coating, and a mineral fiber-reinforced acrylic/vinyl ester back coating interposed between, and molecularly fused to, the core and face coating.